Echo-Tracking Technique in Ultrasonography Can Monitor Changes in Carotid Artery Elastic Function at Early Stage of Intensity-Modulated Radiation Therapy for Nasopharyngeal Carcinoma

BACKGROUND: We used echo-tracking (ET) technique to observe short-term dynamic changes of the carotid artery in nasopharyngeal carcinoma (NPC) patients after intensity-modulated radiation therapy (IMRT). MATERIAL/METHODS: Sixty-one NPC patients received IMRT. In the irradiation group, the carotid artery was examined by ultrasonography before radiotherapy, at 2, 4, and 6 weeks after the start of radiotherapy, and at 3 and 6 months after the end of radiotherapy. In the control group, the carotid artery was examined by ultrasonography before radiotherapy of patients in the irradiation group, and at 3 and 6 months after the end of radiotherapy of patients in the irradiation group. RESULTS: During radiotherapy for the 61 patients, the maximum dose on the carotid artery was 65.14±4.35 Gy, the average dose was 57.46±4.12 Gy, and the 50% volume dose was 51.80±5.32 Gy. At the end of irradiation, Ep (kPa) and β values were significantly different from those before treatment. CONCLUSIONS: The present study demonstrates that the elastic function of the carotid artery can be significantly affected when the irradiation dose exceeds 45 Gy.